Secure FTP is a method of encrypting a standard ftp connection.
I followed the FreshMeat tutorial written by John K Norden when implementing this service:

http://freshmeat.net/articles/view/1576/

“Why would you want to implement something like this?” someone may ask. It’s very simple. Once you have sftp and scp, you can implement encrypted offsite backup, provide a quick and secure method of receiving files from clients, and you never have to say you left your file at home again.